Method of making a hollow metal bat

ABSTRACT

A hollow metal ball bat and method of making the same. The bat is formed from a unitary metal tube having a completely open end at one end thereof and a partially or completely closed, integral end wall at the other end thereof. A portion of the tube including the open end thereof is reformed to provide the portion with a reduced wall thickness which, in turn, is reduced in diameter to form the handle portion of the bat. An intermediate portion of the tube tapers between the handle portion and a barrel portion having the diameter of the original tube and the closed end wall. The reduction in diameter increases the thickness of the wall of the handle portion to a thickness approximating that of the barrel portion of the bat so that the ratio of the weight per unit length of the handle and barrel portions thereof is substantially the same as the ratio of their diameters.

1 1 Apr. 30, 1974 METHOD OF MAKING A HOLLOW METAL BAT [75] Inventors: Eldrich J. Willis, Pittsburgh; David G. Nelson, Allison Park, both of Pa.

[73] Assignee: Aluminum Company of America, Pittsburgh, Pa.

[52] US. Cl. 72/370, 273/72 A [51] Int. Cl B21 d 51/16 [58] Field of Search..... ...27'3/72 572 R; 1fi70 R,"

[56] References Cited UNITED STATES PATENTS 1,499,128 6/1924 Shroyer, Jr. 273/72 2,227,817 1/1941 Allen 72/367 639,532 12/1899 Courtman 72/367 3,596,491 8/1971 Cress .L 72/370 3,602,030 8/1971 Noda 72/347 besko 72/276 Gildemeister 273/72 Primary Examiner-Lowell A. Larson Attorney, Agent, or Firm-Elroy Strickland ABSTRACT A hollow metal ball bat and method of making the same. The bat is formed from a unitary metal tube having a completely open end at one end thereof and a partially or completely closed, integral end wall at the other end thereof. A portion of the tube including the open end thereof is reformed to provide the portion with a reduced wall thickness which, in turn, is reduced in diameter to form the handle portion of the bat. An intermediate portion of the tube tapers between the handle portion and a barrel portion having the diameter of the original tube and the closed end wall. The reduction in diameter increases the thickness of the wall of the handle portion to a thickness approximating that of the barrel portion of the bat so that the ratio of the weight per unit length of the handle and barrel portions thereof is substantially the same as the ratio of their diameters.

5 Claims, 6 Drawing Figures METHOD OF MAKING A HOLLOW METAL BAT BACKGROUND OF THE INVENTION of the bat in order to enhance the ball hitting effectiveness of the bat, and to simulate the weight distribution of a solid wooden bat. Examples of such structures are shown in the Shroyer, Jr. and Middlekaufi US. Pat. Nos. 1,499,128 and 1,611,858, respectively. I

On the other hand, hollow metal bats have been made with a substantially uniform weight per unit length of the bat, for-example, as shown in the Merola U. S. Pat. No. 3,479,030 and as suggested in the Taylor et al. U.S. Pat. No. 2,340,15 6.In the Merola patent, this is accomplished by reducing the diameter of a portion of a metal tube blank in a swaging operation to form the handle portion of the bat, the blank having a substantially uniform starting diameter and wall thickness. As the blank is reduced in diameter, a substantially thickened metal wall is produced in the thus formed handle portion which maintains the abovementioned uniform weight per unit length characteris- K10.

Hollow metal bats have been strengthened in a variety of ways. In the above-mentioned Middlekauff patent, an inner sleeve is secured in thebarrel end ofthe bat along with a weighted insert or plug which closes the barrel end of the bat. In the above Taylor et al. pat'ent, longitudinally extending integral ribs are employed on the inside wall surface of a bat to strengthen the bat.

By virtue of the additional metal and materials of the weights, sleeves, ribs and barrel end plugs as well as the labor and machines involved in making and assembling such structures of the above, prior art bats, costs are added to the bats. In view of such structures, a unitary hollow metal bat is needed in which barrel end plugs are not necessary, and in which a weight distribution is provided that is inherently non-uniform and corresponding to that of a wooden bat without the necessity of adding weights to the barrel end thereof to obtain such a weight distributionJFurther, a hollow metal bat is needed which has a high strength, long life characteristic without the necessity of reinforcing cylinders or integral, internal ribs.

BRIEF SUMMARY OF THE INVENTION The present invention is directed to such a bat, and to a simple method of making the bat, the method providing a saving in metal and cost of the bat without adversely affecting the strength thereof.

Briefly, the present method comprises reforming a finite length of metal tube by machining off a portion of the CD. or preferably by ironing the tube over a tapered mandrel, the reforming process producing a tapered wall and a thin wall portion of the tube of finite length. The tube is then removed from the mandrel and the thinned length of the tube reduced in diameter by a swaging process to form the handle of the bat. The reduction in diameter tends to increase the wall thickness of handle portion to a value similar to that of the remainder of' the metal tube, which remainder includes the barrel or ball striking portion of the bat. In this manner, the ratio of the weight per unit length of the handle and barrel portions of the bat approximates that of the ratio of their diameters, the weight distribution of the bat thereby being non-uniformand approximating that of a solid wooden baseball bat. This is accomplished without reducing the requiredstrength of the handle portion.

As can be appreciated, ironing a tube on a tapered mandrel insures precise control of the relative amount of metal in the handle, taper and barrel portions of the bat, and thus insures an economy of metal and required strength not heretofore realized in bats made without such control. Excess metal in bat handle portions is wasted metal and thus adds costs unnecessarily.

-.If a tube blank is used having a closed, integral wall at one end thereof, further savings are effected in producing the bat since an end plug is not needed for the end having the integral wall thereby saving the costs of the plug and the process of inserting it.

THE DRAWING longitudinal section, and provided with an inward flange at one end thereof) located on a tapered mandrel, and a die for ironing the blank on the mandrel in accordance with the principles of the invention;

FIG. 2 shows the metal tube ironed on the mandrel of FIG. 1;

FIG. 3 shows an alternative embodiment of the invention in which an impact extruded blank or workpiece is ironed on the mandrel of FIG. 1;

FIG. 4 shows the metal tube of FIG. 3 formed into a baseball bat;

FIG. 5 shows the impact extruded blank of FIG. 3 before the tube wall thereof is ironed; and

F IG. 6 shows the blank of FIG. 5 ironed on a mandrel having a configuration different from the mandrel of FIGS. 1 to 3.

PREFERRED EMBODIMENTS OF THE INVENTION In reference to the drawings, FIG. 1 shows, in longitudinal section, a single piece metal tube blank 10 having a generally uniform diameter and wall thickness disposed on a tapered mandrel 12 shown in elevation. The forward (left-hand) extremity of the tube in FIGS. 1 and 2 is shown open but provided with an inwardly directed portion 14. As'shown, however, in FIGS. 3 to 5, one end of the tube blank may be completely closed, for example, as would be provided when a metal slug (not shown) is impact extruded in a well known manner to form a tube blank 15 (FIG. 5) having a closed integral end wall 16.

In FIGS. 1 to 3 of the drawings, the mandrel 12 is de picted as having a firstvportion or section 12a of a substantially constant diameter, and a center section 12b tapering to a third section 12c having a substantially constant diameter that is somewhat less than the constant diameter of the first section. It'should be noted, however, that for the purposes of the invention, the mandrel need not have the three distinct portions shown in FIGS. 1 to 3. For example, the entire length of the mandrel may be uniformly tapered, as suggested in FIG. 6, or the three portions shown in the drawing may have different lengths and degrees of taper. The configuration and dimensions of the mandrel, as well as the wall thickness of the tube blank 10, are selected for a particular desired bat design, since, as explained in greater detail hereinafter, in an ironing process, the

mandrel controls the disposition of metal that ultimately forms the final bat product.

The mandrel 12 is preferably made of hard metal, such as steel, that is highly polished to reduce friction between it and the tube blanks or 15) disposed thereon. The mandrel is mounted in the head 17 of an ironing apparatus or push bench (not shown) which functions to move the mandrel through the opening 19 of a stationary ironing die 18 suitably mounted in a die holder 20 of the apparatus, for the ironing process, and to return the head and mandrel to their original positions after the completion of the ironing process.

To begin the ironing process, a tube blank 10 or 15 is'slipped onto the mandrel 12, with the curved extremity 14 or closed end wall 16 of the blank located adjacent the forward end of the mandrel/The ironing appa ratus is then operated to move the mandrel with the blank thereon into the die opening 19. As the tube engages the die, the curved extremity or end wall of the blank engages the end .of the mandrel to prevent the tube from traveling towards the head 17 as the mandrel moves through the die.

With a tube blank having a constant inner diameter similar to that of portion 12a of the mandrel, as showin in FIG. 1, an annularspace 21 of a substantially constant dimension exists between the blank and mandrel portion 120 while essentially no space exists between the blank and mandrel portion 12a. Between mandrel portion 12b and the blank, a tapered annular space 22 exists.

The relative diameters of the die opening 19 and tube blank 10 or 15 are such that as the forward section of blank and the reduced diameter portion 12c of the mandrel are moved through the die, the die radially reforms and reduces the forward section of the blank through the annular-space 21 onto the reduced portion of the mandrel without little or no reduction of the wall thickness of the blank. As the tapered portion 12b of the mandrel moves through the die with the blank, the die begins to reform and reduce the diameter of the blank but because of the decreasing annular space 22 the blank and mandrel into the die opening 19, the type or reduction, as discussed above, depending upon the configuration of the mandrel, the inner diameter of the blank and outer diameter of the mandrel.

As the mandrel and tube blank continue through the die 18 in the embodiments of FIGS. 1 to 3, the section of the blank on mandrel portion 12a is ironed thereon as the metal of the blank wall flows toward the rear of the mandrel thereby substantially uniformly reducing the thickness of that section of the blank wall. In FIG. 2, the sections of the blank are labelled 10a, b and c corresponding to the portions 12a, b and c of the mandrel.

FIGS. 2 and 3 show respectively the tube blanks 10 and 15 on the mandrel 12 at the end of the ironing process. As shown, the length of the blanks are substantially increased by the ironing process, and the forward section of the tube blank 10 (on portion of the mandrel) has a relative thick wall while the rear section 10a of blank (on portion 12a of the mandrel) has a relatively thin wall. The wall of the intermediate section 10b of the blank has a wall thickness that tapers in a decreasing manner from the forward section of the blank to the rearward section thereof.

It should be understood that a tube blank with a tapered and controlled wall may be produced by other known processes, such as machining over a mandrel; the blank must however approximate the same baxic configuration obtained by the preferred method of ironing.

The ironed tube blank 10, as shown'in FIG. 2, is next removed from the tapered mandrel l2, and positioned in a swaging machine (not shown) for reducing the diameter of the ironed, thin wall section 10a of the blank to form the handle portion 23 of an open ended bat 24, as shown in FIG. 4. The barrel or ball striking portion 25 of the bat remains at the original diameter of the ironed blank while the diameter of the intermediate area 27 of the bat tapers between the handle and barrel portions. Y

'As the handle portion 23 is formed, i.e'., reduced in diameter, the wall thickness of the handle portion tends to increase until it, along with the tapered portion adjacent the handle portion, attains essentially the original thickness of the tube blank 10. In this manner, the ratio of the weight per unit length of the handle, tapered and barrel portions is substantially the same as ratio of their I portions of the bat. (The original wall thickness of the blank can'be used to control the amount of metal in the barrel portion of the bat.) As explained. earlier, the dimension and configuration of the mandrel can be chosen to control the distribution of metal in any suitable manner, and thus handle wall thicknesses, for substantially any desired type of bat design.

In this regard, the mandrel portion 12a may have a tapered end increasing toward the head 17 of the push bench to provide a thin wall portionat the extremity of the bat handle remote from its tapered portion 27. At this extreme end of the bat, a thick wall and high strength are not necessary.

In a similar manner, the mandrel portion 12c may be inwardly tapered toward its free end to provide a wall portion for the barrel end of the bat that is thicker than the remaining wall portions of the bat. This would provide additional weight at the barrel end for strength and a more effective bat.

The swaging, diameter reducing process of forming the handle portions of the bat 24 is preferably performed on a second mandrel (not shown) located within the swaging machine, the second mandrel providing further control of the wall thickness of the handle portion.

In order not to effect substantially the weight distribution of the final bat product, the open ends thereof are preferably closed with plugs made of a light weight, shock resistant material, such as rubber or a polyvinyl chloride plastic. With the bat of FIG. 4, made from the open ended tube blank of FIGS. 1 and 2, the ends thereof are respectively closed with such light weight plugs. In FIG. 4 only a plug and integral grip 30 are shown (in dash outline) since the barrel end 25 has the closed, integral end wall 16.

In one embodiment of the invention, for a final bat length (not including end plugs) of about 34 inches using an aluminum alloy, the smaller constant diameter portion 12c of the mandrel is approximately 14 inches long with a diameter of about 1.842inches. The length of the intermediate portion 12b of the mandrel for such a bat is about 10.5 inches with a diameter tapered from the 1.842 diameter of portion 12c to a 1.920 inch diameter for portion 12a of the mandrel. The dimensions of the aluminum tube blank 10 for such a mandrel are (1) an outside diameter of 2.086 inches, (2) an inside diameter 1.928 inches (slightly larger than that of the portion 12a of the mandrel and providing an initial blank thickness of 0.158 2 or 0.079 inches), and (3) a length of about 26 inches. The opening 19 of the die 18 is 2.000 inches in diameter. With such a mandrel, tube blank and die opening, after the ironing process, the wall thickness of section 100 of the blank on mandrel portion 12c remains at 0.079 inches while the wall thickness of the blank on the mandrel portion 12a is reduced to about 0.040 inchesJThe increase in length of the blank is about 8 inches, i.e., from 26 to 34 inches. When the 0.040 inch portion is reduced in diameter to form the handle portion 23 of bat 24, the wall of the portion increases in thickness to a dimension similar to that of the barrel portion 25. If the bat is cut in equal sections along its length, it would be found that'the ratio of the weight per unit length of its=handle and barrel portions would be substantially the same as the ratio of their respective diameters. This would be true for bats having a taper from end to end, i.e., for bats having' no constant diameter portions. The average of diameters along the handle and barrel portions of the bat would be used to determine the ratio of the weight per unit length for the two portions.

From the foregoing description it should now be apparent that a new and useful ball bat, and method of making the same, has been disclosed, the bat having a non-uniform weight distribution approximating that of a solid wooden baseball bat. The method provides a increase to a thickness dimension approximating that of the original tube blank and the barrel portion of the bat. Further economies are effected by using a tube highly economical use of metal without sacrificing nechaving a closed, integral end wall thereby eliminating the need of an end plug.

While the invention has been described in terms of preferred embodiments, the claims appended hereto are intended to encompass all embodiments which fall within the spirit and scope of the invention.

Having thus described our invention and certain embodiments thereof, we claim:

1. A method of making a hollow metal ball bat having a substantially uniform wall thickness along the length thereof, the metal bat comprising an elongated hollow metal body having a cylindrical barrel portion of one outer diameter, a cylindrical handle portion of reduced outer diameter and an intermediate portion tapering between said barrel and handle portions, the method comprising the steps of ironing asingle piece, seamless, hollow metal tube having essentially a uniform wall thickness along the length thereof on a tapered mandrel to provide the metal tube with a decreased wall thickness in the area thereof that will provide the handle portion for said bat,

removing the metal tube from the tapered mandrel,

and

reducing the outer diameter of the metal tube in the area thereof having the decreased wall thickness to form the handle portion of said bat and the tapering portion intermediate the handle and barrel portions, the wall thicknesses of the handle and intermediate portions at the completion of the reducing step being substantially the same as the uniform wall thickness of the hollow metal tube such that the ratio of the weight per unit length of the handle and barrel portions of the bat is substantially the same as the ratio of their diameters whereby the weight distribution of the final bat is determined substantially solely by the ratio of the diameters of 1 the handle and barrel portions. 2. The method of claim 1 wherein the metal tube has an inwardly curved extremity which engages the forward end of the tapered mandrel for the ironing step.

565s of the ball bat. said second mandrel providing further control of wall thickness in the portion of the metal tube having the decreased wall thickness.

5. The method of claim 1 wherein the metal tube is ironed on a mandrel having two, spaced constant diameter portions of different diameters, and an intermediate, tapered portion extending between said constant diameter portions. 

1. A method of making a hollow metal ball bat having a substantially uniform wall thickness along the length thereof, the metal bat comprising an elongated hollow metal body having a cylindrical barrel portion of one outer diameter, a cylindrical handle portion of reduced outer diameter and an intermediate portion tapering between said barrel and handle portions, the method comprising the steps of ironing a single piece, seamless, hollow metal tube having essentially a uniform wall thickness along the length thereof on a tapered mandrel to provide the metal tube with a decreased wall thickness in the area thereof that will provide the handle portion for said bat, removing the metal tube from the tapered mandrel, and reducing the outer diameter of the metal tube in the area thereof having the decreased wall thickness to form the handle portion of said bat and the tapering portion intermediate the handle and barrel portions, the wall thickneSses of the handle and intermediate portions at the completion of the reducing step being substantially the same as the uniform wall thickness of the hollow metal tube such that the ratio of the weight per unit length of the handle and barrel portions of the bat is substantially the same as the ratio of their diameters whereby the weight distribution of the final bat is determined substantially solely by the ratio of the diameters of the handle and barrel portions.
 2. The method of claim 1 wherein the metal tube has an inwardly curved extremity which engages the forward end of the tapered mandrel for the ironing step.
 3. The method of claim 1 wherein the metal tube is an impact extruded workpiece providing a closed end wall which engages the forward end of the tapered mandrel for the ironing step.
 4. The method of claim 1 including the steps of disposing at least the portion of the hollow metal tube having the decreased wall thickness on a second mandrel, and reducing the diameter of said tube portion on said second mandrel to provide further control of wall thickness in the portion of the metal tube having the decreased wall thickness.
 5. The method of claim 1 wherein the metal tube is ironed on a mandrel having two, spaced constant diameter portions of different diameters, and an intermediate, tapered portion extending between said constant diameter portions. 